What is the proof that gas giants have magnetic fields?

Gas giants like Jupiter and Saturn have strong magnetic fields, which are evidenced by their magnetospheres and the behavior of charged particles in their vicinity. The presence of metallic hydrogen in their interiors, generated by the extreme pressure and temperatures, contributes to their magnetic fields through dynamo action. Observations from spacecraft, such as the Galileo orbiter around Jupiter, have directly measured the magnetic fields, revealing their intensity and structure. Additionally, auroras observed at their poles indicate the interaction of their magnetic fields with solar wind, further confirming their existence.